The Possibility for Cavitation-Free Materials Synthesis and Processing?
Cavitation arising from high intensity ultrasound has long been known to enable a host of chemical reactions and manipulation—a field known as 'sonochemistry’, with wide ranging implications for many processes including catalysis, polymerisation, crystallisation, among others. Recently, however, the possibility for cavitation-free sonochemistry has been conjectured (Vinatoru & Mason, Ultrason Sonochem 52, 2, 2019), although evidence for such has yet to be revealed.
For the first time, we show that cavitation-free sonochemistry is indeed possible with higher frequencies beyond that of conventional ultrasound (10 MHz and above) associated with surface acoustic wave (SAW) and its hybrid counterpart (surface reflected bulk waves; SRBW) excitation where we have demonstrated cavitation to essentially be non-existent for the intensities employed (Rezk et al., J Phys Chem Lett 11, 4655, 2020). Below, we provide examples of how the highly nonlinear electromechanical coupling associated with the high frequency surface vibration associated with the SAW or SRBW gives rise to a variety of static and dynamic charge generation and transfer effects, in addition to molecular ordering, polarisation and assembly phenomena—quite remarkably, given the vast dimensional separation between the acoustic wavelength and characteristic molecular length scales—can be exploited for the synthesis, manipulation and processing of bulk and two-dimensional materials. These include crystallisation of novel morphologies or highly oriented structures; the exfoliation of two-dimensional quantum dots, nanosheets and large flakes from bulk materials; polymer nanoparticle synthesis and encapsulation; and, the possibility for manipulating the bandgap of two-dimensional semiconducting materials or the lipid structure that makes up the bilayer membrane of cells, the latter resulting in the ability to drive a diverse cell mechanostimulatory responses.
These first demonstrations are therefore expected to open up an entire new field with wide-ranging possibilities for the synthesis and processing of a host of novel materials.
Representative Publications
For the first time, we show that cavitation-free sonochemistry is indeed possible with higher frequencies beyond that of conventional ultrasound (10 MHz and above) associated with surface acoustic wave (SAW) and its hybrid counterpart (surface reflected bulk waves; SRBW) excitation where we have demonstrated cavitation to essentially be non-existent for the intensities employed (Rezk et al., J Phys Chem Lett 11, 4655, 2020). Below, we provide examples of how the highly nonlinear electromechanical coupling associated with the high frequency surface vibration associated with the SAW or SRBW gives rise to a variety of static and dynamic charge generation and transfer effects, in addition to molecular ordering, polarisation and assembly phenomena—quite remarkably, given the vast dimensional separation between the acoustic wavelength and characteristic molecular length scales—can be exploited for the synthesis, manipulation and processing of bulk and two-dimensional materials. These include crystallisation of novel morphologies or highly oriented structures; the exfoliation of two-dimensional quantum dots, nanosheets and large flakes from bulk materials; polymer nanoparticle synthesis and encapsulation; and, the possibility for manipulating the bandgap of two-dimensional semiconducting materials or the lipid structure that makes up the bilayer membrane of cells, the latter resulting in the ability to drive a diverse cell mechanostimulatory responses.
These first demonstrations are therefore expected to open up an entire new field with wide-ranging possibilities for the synthesis and processing of a host of novel materials.
Representative Publications
- K Kulkarni, J Friend, L Yeo, P Perlmutter. Surface Acoustic Waves as an Energy Source for Drop Scale Synthetic Chemistry. Lab Chip 9, 754-755 (2009).
- KP Kulkarni, SH Ramarathinam, J Friend, L Yeo, AW Purcell, P Perlmutter. Rapid Microscale In-Gel Processing and Digestion of Proteins Using Surface Acoustic Waves. Lab Chip 10, 1518–1520 (2010).
- K Kulkarni, J Friend, L Yeo, P Perlmutter. An Emerging Reactor Technology for Chemical Synthesis: Surface Acoustic Wave-Assisted Closed-Vessel Suzuki Coupling Reactions. Ultrason Sonochem 21, 1305–1309 (2014).
- AR Rezk, H Ahmed, TL Brain, JO Castro, MK Tan, J Langley, N Cox, J Mondal, W Li, M Ashokkumar, LY Yeo. Free Radical Generation from High Frequency Electromechanical Dissociation of Pure Water. J Phys Chem Lett 11, 4655–4661 (2020).
- AR Rezk, H Ahmed, S Ramesan, LY Yeo. High Frequency Sonoprocessing: A New Field of Cavitation-Free Acoustic Materials Synthesis, Processing and Manipulation. Invited paper: Adv Sci 8, 2001983 (2021).
- Y Ehrnst, H Alijani, C Bentley, PC Sherrell, BJ Murdoch, LY Yeo, AR Rezk. UNLEASH: Ultralow Nanocluster Loading of Pt via Electro-Acoustic Seasoning of Heterocatalysts. Adv Mater 37, 2409495 (2025).
- Ultrasound Makes Nano-Waves, Generating ‘Green’ Radicals. Chemistry World, 26 June 2020 (Royal Society of Chemistry).
- Sound Waves Power New Advances in Drug Delivery and Smart Materials. The National Tribune, 24 November 2020.
- Bizarre Effects of Sound Waves Could Benefit Drug Delivery, Exosome Therapy. Bio-IT World, 6 January 2021.
Synthesis and Manipulation of Novel Bulk & Two-Dimensional Crystals and Quantum DotsThe large surface acceleration associated with MHz-order surface acoustic wave (SAW) vibration—on the order of 10 million g’s—can be exploited for rapid micro/nanoscale material processing, for example, the debundling carbon nanotube agglomerates, or, for the synthesis of crystalline materials. In the latter, the unique evaporation rate regimes that can be accessed have given rise to novel crystal morphologies, previously undiscovered. Moreover, the large mechanical stresses arising from the strong surface acceleration, together with the high intensity electric field inherent in the electromechanical coupling of the acoustic wave during SAW microcentrifugation and nebulisation, can also be used to rapidly tuneably exfoliate bulk three-dimensional crystalline transition metal dichalcogenides such as molybdenum disulphide (MoS2) and transition metal carbides/nitrides (MXenes) into monolayer and few-layer quantum dots, nanosheets as well as large micron-dimension sheets with the potential for high yield. Further, we observe the possibility of rapidly synthesizing powders comprising metal–organic frameworks (MOFs), which, quite unexpectedly, not just appear to be highly oriented but are also simultaneously activated during the process.
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Representative Publications
- M Miansari, A Qi, LY Yeo, JR Friend. Vibration-Induced Deagglomeration and Shear-Induced Alignment of Carbon Nanotubes in Air. Adv Funct Mater 25, 1014–1023 (2015) [Article coverart selected as journal front cover 7/2015 p 989].
- H Ahmed, L Lee, C Darmanin, LY Yeo. A Novel Acoustomicrofluidic Nebulization Technique Yielding New Crystallization Morphologies. Adv Mater 30, 1602040 (2018) [Article coverart selected as journal frontispiece 30, 1870018].
- S Marqus, H Ahmed, M Ahmed, C Xu, AR Rezk, LY Yeo. Increasing Exfoliation Yield in the Synthesis of MoS2 Quantum Dots for Optoelectronic and Other Applications through a Continuous Multicycle Acoustomicrofluidic Approach. ACS Appl Nano Mater 1, 2503–2508 (2018).
- M Mohiuddin, Y Wang, A Zavabeti, N Syed, RS Datta, H Ahmed, T Daeneke, SP Russo, AR Rezk, LY Yeo, K Kalantar-zadeh. Liquid Phase Acoustic Wave Exfoliation of Layered MoS2: Critical Impact of Electric Field in Efficiency. Chem Mater 30, 5593–5601 (2018) [Article featured in ACS Editors’ Choice].
- H Ahmed, AR Rezk, BJ Carey, Y Wang, M Mohiuddin, KJ Berean, SP Russo, K Kalantar-zadeh, LY Yeo. Ultrafast Acoustofluidic Exfoliation of Stratified Crystals. Adv Mater 30, 1704756 (2018).
- M Ahmed, H Ahmed, AR Rezk, LY Yeo. Rapid Dry Exfoliation Method for Tuneable Production of Molybdenum Disulphide Quantum Dots and Large Micron-Dimension Sheets. Nanoscale 11, 11626–11633 (2019).
- H Ahmed, AR Rezk, JJ Richardson, LK Macreadie, R Babarao, ELH Mayes, L Lee, LY Yeo. Acoustomicrofluidic Assembly of Oriented and Simultaneously Activated Metal–Organic Frameworks. Nature Commun 10, 2282 (2019).
- H Ahmed, X Yang, Y Ehrnst, NN Jeorje, S Marqus, PC Sherrell, A El Ghazaly, J Rosen, AR Rezk, LY Yeo. Ultrafast Assembly of Swordlike Cu3(1,3,5-Benzenetricarboxylate)n Metal–Organic Framework Crystals with Exposed Active Metal Sites. Nanoscale Horiz 5, 1050–1057 (2020) [Article coverart selected as journal front cover].
- S Marqus, H Ahmed, AR Rezk, T Huynh, A Lawrie, D Nguyen, Y Ehrnst, C Dekiwadia, LY Yeo. Enhanced Antimicrobial Activity and Low Phytotoxicity of Acoustically-Synthesized Pseudo-One-Dimensional Cu-BTC Metal–Organic Frameworks with Exposed Metal Sites. ACS Appl Mater Interfaces 13, 58309–58318 (2021).
- A El Ghazaly, H Ahmed, A Rezk, J Halim, P Persson, LY Yeo, J Rosen. Ultrafast, One-Step, Salt-Solution-Based Acoustic Synthesis of Ti3C2 MXene. ACS Nano 15, 4287–4293 (2021).
- H Alijani, AR Rezk, MM Khosravi Farsani, H Ahmed, J Halim, P Reineck, BJ Murdoch, A El-Ghazaly, J Rosen, LY Yeo. Acoustomicrofluidic Synthesis of Pristine Ultrathin Ti3C2Tz MXene Nanosheets and Quantum Dots. ACS Nano 15, 12099–12108 (2021).
- Y Ehrnst, H Ahmed, R Komljenovic, E Massahud, NA Shepelin, PC Sherrell, AV Ellis, AR Rezk, LY Yeo. Acoustotemplating: Rapid Synthesis of Freestanding Quasi-2D MOF/Graphene Oxide Heterostructures for Supercapacitor Applications. J Mater Chem A 10, 7058–7072 (2022) [Article coverart selected as journal inner back cover].
- E Massahud, H Ahmed, LA Ambattu, AR Rezk, LY Yeo. Acoustomicrofluidic Synthesis of ZIF-8/HRP Metal–Organic Framework Composites with Enhanced Enzymatic Activity and Stability. Mater Today Chem 33, 101694 (2023).
- E Massahud, H Ahmed, R Babarao, Y Ehrnst, H Alijani, C Darmanin, BJ Murdoch, AR Rezk, LY Yeo. Acoustomicrofluidic Defect Engineering and Ligand Exchange in ZIF-8 Metal–Organic Frameworks. Small Methods 7, 2201170 (2023).
- H Ahmed, H Alijani, A El-Ghazaly, J Halim, BJ Murdoch, Y Ehrnst, E Massahud, AR Rezk, J Rosen, LY Yeo. Recovery of Oxidized Two-Dimensional MXenes Through High Frequency Nanoscale Electromechanical Vibration. Nature Commun 14, 3 (2023).
- Researchers Hear About New, Efficient Way to Create MOFs. Materials Today, 7 June 2019 (Elsevier).
- Sounds Like a Longer-Lasting Battery. Materials Today, 27 January 2023 (Elsevier).
- Why MXenes Matter. IEEE Spectrum, 23 February 2023.
- Sounds Good. Nature Energy Research Highlights 27 January 2023. Nature Energy 8, 7 (2023).
Acoustic Modulation & Manipulation of Two-Dimensional MaterialsOur pioneering fundamental work has shown the ability to manipulate quasiparticles in two-dimensional materials such as monolayer and few-layer molybdenum disulphide (MoS2) using acoustic fields. Specifically, we have demonstrated the possibility for reversibly modulating the trion to exciton transition and their subsequent transport and hence spatial separation within the material. Additionally, we have also shown the possibility of manipulating the bandgap of tin sulphide (SnS2) through a unique and novel tripartite phonon–photon–electron coupling, that together with providing the requisite momentum for indirect bandgap transition of photoexcited charge carriers, enables broadband photodetection at wavelengths considerably higher than that for visible light.
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Representative Publications
- AR Rezk, B Carey, AF Chrimes, DWM Lau, BC Gibson, C Zheng, MS Fuhrer, LY Yeo, K Kalantar-zadeh. Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS2. Nano Lett 16, 849–855 (2016).
- AR Rezk, S Walia, R Ramanathan, H Nili, JZ Ou, V Bansal, JR Friend, M Bhaskaran, LY Yeo, S Sriram. Acoustic–Excitonic Coupling for Dynamic Photoluminescence Manipulation of Quasi-2D MoS2 Nanoflakes. Adv Opt Mater 3, 888–894 (2015) [Article coverart selected as journal front cover].
- H Alijani, P Reineck, R Komljenovic, SP Russo, MX Low, S Balendhran, KB Crozier, S Walia, GR Nash, LY Yeo, AR Rezk. The Acoustophotoelectric Effect: Efficient Phonon–Photon–Electron Coupling in Zero-Voltage-Biased 2D SnS2 for Broadband Photodetection. ACS Nano 17, 19254–19264 (2023).
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Surface Phonon-Polariton Coupling in Monolithic Phononic CrystalsSAW phononic band gap structures, in which phonons are prohibited from propagating, arising from surface phonon-polariton coupling in two-dimensional structures are demonstrated in monolithic phononic crystals that are completely mechanically, electromagnetically and topographically homogeneous, thus opening up new possibilities for a wide range of acoustic-optic and acoustofluidic applications.
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Representative Publications
- D Yudistira, A Boes, B Djafari-Rouhani, Y Pennec, LY Yeo, A Mitchell, JR Friend. Monolithic Phononic Crystals with a Surface Acoustic Band Gap from Surface Phonon-Polariton Coupling. Phys Rev Lett 113, 215503 (2014).
- D Yudistra, A Boes, AR Rezk, LY Yeo, JR Friend, A Mitchell. UV Direct Write Metal Enhanced Redox (MER) Domain Engineering for Realization of Surface Acoustic Devices on Lithium Niobate. Adv Mater Interfaces 1, 1400006 (2014) [Article coverart selected for journal back cover].
- D Yudistira, A Boes, B Dumas, AR Rezk, M Yousefi, B Djafari-Rouhani, LY Yeo, A Mitchell. Phonon-Polariton Entrapment in Homogenous Surface Phonon Cavities. Ann Phys 528, 365–372 (2016) [Article coverart selected for journal back cover p 434].
- D Yudistira, A Boes, B Graczykowski, F Alzina, LY Yeo, CM Sotomayor Torres, A Mitchell. Nanoscale Pillar Hypersonic Surface Phononic Crystals. Phys Rev B 94, 094304 (2016).
- BJ Ash, AR Rezk, LY Yeo, GR Nash. Subwavelength Confinement of Propagating Surface Acoustic Waves. Appl Phys Lett 118, 013502 (2021).
